Using the Glycemic Index to Choose Carbs

Q: What the heck is all the hoopla over the Glycemic Index (GI) of food? Can you explain to me why peanut M&M's
are lower GI than rice cakes, and what this really tells me? How in the world can I incorporate
yet another confusing piece of information into making appropriate food choices?

G.I. Background

A: Now before all of you go running to the store to stock up on peanut
M&M's, here's a little background. First of all, each of us (not just
diabetics) could benefit from an understanding of the Glycemic Index of food,
which measures how quickly carbohydrates/sugars are converted to blood sugar (or
glucose.) Glucose itself is set as the standard, and rated at 100
(although there's another scale that uses white bread as the standard at
100-check your chart to see what is what). All other carbohydrates are
then rated in relationship to glucose. Foods high in GI release glucose
very quickly, resulting in an energy spike that sustains you for mere
minutes. Foods low in GI release glucose more slowly, resulting in more
sustained energy over several hours.

In other words, carbohydrates are NOT equal. The GI rating also does
NOT entirely depend merely on whether a food is a simple or complex
carbohydrate. Factors that affect the GI include: 1) quantity of fiber
(the more fibrous, the longer it takes to digest and absorb, the lower the GI);
2) how easily the food is actually digested (anything with protein or fat takes
longer to digest, hence lowering the total GI of what you're eating); 3)
quantity of specific sugars (fructose converts slowly, maltose more quickly),
and 4) the form in which the food is eaten. Cooking or pre-cooking can
also raise the GI--quick cooking oatmeal is much higher than slow-cooked
oatmeal. Liquids are more quickly assimilated by the body, hence one of
the values of consuming a post-workout drink immediately after a hard workout
,when you want to replenish muscle glycogen as quickly as possible.

Combining and Timing

How, then, can you properly incorporate the higher GI foods such as
bananas, bagels, potatoes, carrots, raisins, bread, rice, cereals, and so on
that most of us have grown to love so much? COMBINING and TIMING. By
combining a high GI food with protein, fat, or low GI carbs, you reduce the
overall GI rating, resulting in satiation over a longer period of time.
Result? Less consumed over time, and, ultimately, weight loss! Go
ahead and add a bit of cream cheese or peanut butter to that bagel. Have
some yogurt with the cereal. Have a small amount of butter on the bread,
or better yet, make it a turkey or tuna sandwich.

Furthermore, the BEST time to eat those high GI foods is immediately
following any strenuous workout when the muscles are depleted of glycogen.
That's why it's so common to see bananas and bagels at the finish lines of
marathons, triathlons, and other endurance events. However, make sure that
the meal preceding your endurance workouts is full of lower GI foods so that you
can prevent "bonking" or "hitting the wall."

Carb Craving Cycle

Now you may begin to see how craving carbohydrates can result in weight
gain: whenever glucose enters the bloodstream, insulin is secreted, delivering
glucose to the cells for energy use OR storage as body fat. Sometimes the
body overreacts in the presence of a sudden surge of glucose (as happens when
you skip meals and have high GI foods on an empty stomach) and produces too much
insulin, which then increases the tendency to store fat and also LOWERS your
blood sugar levels, creating a vicious cycle of carb craving.

As for the initial question above, regarding rice cakes (rated 110) vs.
peanut M&M's (chocolate, rated 70, combined with peanuts, rated 21, which
makes the total GI about 55) if you compare calorie for calorie, the
peanut-containing M&M's will leave you feeling a lot more satisfied than
puffed rice, and not merely because of the flavor and texture. That may
indeed mean stopping at just 6 peanut M&M's as opposed to 3 whole rice cakes
or 6 carrots, but have you noticed how hungry you still feel after having those
carrots or rice cakes?? So much for calling them "diet foods"--they may as well be "anti-diet foods!"

Here is a sample of popular carbohydrates and where they rate. For a
much more complete listing, visit Rick
Mendosa's Glycemic Index of foods. These are compared with white bread, given a rating of 100.